released. A layer of net of wire mesh lied underneath the layer of soil bed to enable
water to stream down while holding the earthworms in the soil bed because it can
slither down to filter materials. It is reported that around 1 week settling time in the
soil bed is required for earthworms to acclimatize in the new environment as they
play an important role in wastewater purification (Manyuchi et al. 2013a, b). After
acclimatization, the burrows and castings are reported to form as the earthworm
ingestion activities help in the removal of pollutants from the wastewater
(Domínguez 2004). The wastewater is sprinkled on the upper top layer comprising
of soil that is rich in microbes and earthworms. The passage of the wastewater
through several layers of the vermifiltration system helps in the removal of pollutants. The treated wastewater can be collected at the bottom in the effluent collection
tank (Ghatnekar et al. 2010; Singh et al. 2017). Vermifilters can be considered as an
appropriate small-scale wastewater treatment, particularly in economical terms
(Jiang et al. 2016). Figure 3.1 depicts a schematic representation of vermifiltration
system.
3.2.2 Vermifiltration Process
The process of vermifiltration entails amalgamation of three steps, i.e., primary
(removal of grit, silt, and so forth), secondary (biological degradation), and tertiary
(removal of pathogens) treatment. Vermifiltration is the procedure of wastewater
remediation that includes the joint action of earthworms and microbes. The treated
wastewater might be reused for further applications (Dash 1978; Sinha et al. 2008).
The ingestion and grinding of soil particles along with pollutants by earthworms
results in the alteration of physical, chemical, and biological characteristics of
wastewater (Edwards and Arancon 2004; Liu et al. 2012).
Vermibed and earthworms play an exquisite function in the removal of pollutants
from wastewater. Apart from being a food supply to the earthworms, it helps in
multiplication of microbes (Liu et al. 2013; Zhao et al. 2010). Burrowing of
earthworms involves actions consisting of ingestion, grinding, digestion, and excretion (Aira et al. 2007; Suthar and Singh 2008). The joint effect of these actions
results in numerous physical, chemical, and biological changes on the vermiatmosphere. The fine particles are obtained through the grinding of the ingested
substances within the excreted casting that offer higher filtration efficiency of solids
(Komarowski 2001; Wang et al. 2011).
Burrowing and channeling activity of earthworms helps in expanding waterdriven conductivity of bedding media to get an ideal time of interaction resulting
in an efficient wastewater treatment (Aira and Domínguez 2009; Bhawalkar 1995).
This is also one of the central points behind maintaining oxygen-consuming condition inside the vermibed. The addition of earthworms to the bedding consequently
increases the microbial population inside vermifilter, as earthworms have massive
variety of microbial flora in their gut and discharge them directly to the soil (Arora
et al. 2014). The discharged nutrients in the form of vermin-castings are further
3 Treatment of Wastewater by Vermifiltration Integrated with Plants
39
water to stream down while holding the earthworms in the soil bed because it can
slither down to filter materials. It is reported that around 1 week settling time in the
soil bed is required for earthworms to acclimatize in the new environment as they
play an important role in wastewater purification (Manyuchi et al. 2013a, b). After
acclimatization, the burrows and castings are reported to form as the earthworm
ingestion activities help in the removal of pollutants from the wastewater
(Domínguez 2004). The wastewater is sprinkled on the upper top layer comprising
of soil that is rich in microbes and earthworms. The passage of the wastewater
through several layers of the vermifiltration system helps in the removal of pollutants. The treated wastewater can be collected at the bottom in the effluent collection
tank (Ghatnekar et al. 2010; Singh et al. 2017). Vermifilters can be considered as an
appropriate small-scale wastewater treatment, particularly in economical terms
(Jiang et al. 2016). Figure 3.1 depicts a schematic representation of vermifiltration
system.
3.2.2 Vermifiltration Process
The process of vermifiltration entails amalgamation of three steps, i.e., primary
(removal of grit, silt, and so forth), secondary (biological degradation), and tertiary
(removal of pathogens) treatment. Vermifiltration is the procedure of wastewater
remediation that includes the joint action of earthworms and microbes. The treated
wastewater might be reused for further applications (Dash 1978; Sinha et al. 2008).
The ingestion and grinding of soil particles along with pollutants by earthworms
results in the alteration of physical, chemical, and biological characteristics of
wastewater (Edwards and Arancon 2004; Liu et al. 2012).
Vermibed and earthworms play an exquisite function in the removal of pollutants
from wastewater. Apart from being a food supply to the earthworms, it helps in
multiplication of microbes (Liu et al. 2013; Zhao et al. 2010). Burrowing of
earthworms involves actions consisting of ingestion, grinding, digestion, and excretion (Aira et al. 2007; Suthar and Singh 2008). The joint effect of these actions
results in numerous physical, chemical, and biological changes on the vermiatmosphere. The fine particles are obtained through the grinding of the ingested
substances within the excreted casting that offer higher filtration efficiency of solids
(Komarowski 2001; Wang et al. 2011).
Burrowing and channeling activity of earthworms helps in expanding waterdriven conductivity of bedding media to get an ideal time of interaction resulting
in an efficient wastewater treatment (Aira and Domínguez 2009; Bhawalkar 1995).
This is also one of the central points behind maintaining oxygen-consuming condition inside the vermibed. The addition of earthworms to the bedding consequently
increases the microbial population inside vermifilter, as earthworms have massive
variety of microbial flora in their gut and discharge them directly to the soil (Arora
et al. 2014). The discharged nutrients in the form of vermin-castings are further
3 Treatment of Wastewater by Vermifiltration Integrated with Plants
39